1. Field
Apparatuses and methods consistent with exemplary embodiments relate to an electrochromic device that is excellent in durability when repeatedly switching between a transparent state and a reflective state.
2. Description of the Related Art
Devices that switch between a light transmissive mode and a light reflective mode when a voltage is applied to the devices may be referred to as reflective type electrochromic devices (ECDs).
Generally, a reflective type ECD includes a stacked structure that includes a transparent substrate, a transparent electrode, an ion storage layer, an electrolytic layer, a catalyst layer, and an active layer.
The ion storage layer may be made of a transition metal oxide, and protons (in general, hydrogen ions) stored in the ion storage layer move toward the active layer when a voltage is applied.
The active layer has an optical characteristic which is switched from a reflective state to a transmissive state according to movement of the protons. Meanwhile, when a reverse voltage is applied, the protons move to the ion storage layer which is an original position, and the optical characteristic of the active layer is switched back to the reflective state again. As described above, while reversible oxidation-reduction reaction occurs, the optical characteristic is switched between the transmissive mode and the reflective mode.
In order to increase transmission in the transmissive mode, the amount of stored protons should be large, and in order to increase the amount of stored protons, a thickness of the ion storage layer is usually increased. However, when the thickness of the ion storage layer is increased, time at which proton ions are ejected from the ion storage layer is relatively increased and a whole switching speed of the device is reduced.